libavcodec/mjpegbdec.c

   1 /*
   2  * Apple MJPEG-B decoder
   3  * Copyright (c) 2002 Alex Beregszaszi
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file libavcodec/mjpegbdec.c
  24  * Apple MJPEG-B decoder.
  25  */
  26
  27 #include "avcodec.h"
  28 #include "mjpeg.h"
  29 #include "mjpegdec.h"
  30
  31 static uint32_t read_offs(AVCodecContext *avctx, GetBitContext *gb, uint32_t size, const char *err_msg){
  32     uint32_t offs= get_bits_long(gb, 32);
  33     if(offs >= size){
  34         av_log(avctx, AV_LOG_WARNING, err_msg, offs, size);
  35         return 0;
  36     }
  37     return offs;
  38 }
  39
  40 static int mjpegb_decode_frame(AVCodecContext *avctx,
  41                               void *data, int *data_size,
  42                               AVPacket *avpkt)
  43 {
  44     const uint8_t *buf = avpkt->data;
  45     int buf_size = avpkt->size;
  46     MJpegDecodeContext *s = avctx->priv_data;
  47     const uint8_t *buf_end, *buf_ptr;
  48     AVFrame *picture = data;
  49     GetBitContext hgb; /* for the header */
  50     uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs;
  51     uint32_t field_size, sod_offs;
  52
  53     buf_ptr = buf;
  54     buf_end = buf + buf_size;
  55
  56 read_header:
  57     /* reset on every SOI */
  58     s->restart_interval = 0;
  59     s->restart_count = 0;
  60     s->mjpb_skiptosod = 0;
  61
  62     init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);
  63
  64     skip_bits(&hgb, 32); /* reserved zeros */
  65
  66     if (get_bits_long(&hgb, 32) != MKBETAG('m','j','p','g'))
  67     {
  68         av_log(avctx, AV_LOG_WARNING, "not mjpeg-b (bad fourcc)\n");
  69         return 0;
  70     }
  71
  72     field_size = get_bits_long(&hgb, 32); /* field size */
  73     av_log(avctx, AV_LOG_DEBUG, "field size: 0x%x\n", field_size);
  74     skip_bits(&hgb, 32); /* padded field size */
  75     second_field_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "second_field_offs is %d and size is %d\n");
  76     av_log(avctx, AV_LOG_DEBUG, "second field offs: 0x%x\n", second_field_offs);
  77
  78     dqt_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dqt is %d and size is %d\n");
  79     av_log(avctx, AV_LOG_DEBUG, "dqt offs: 0x%x\n", dqt_offs);
  80     if (dqt_offs)
  81     {
  82         init_get_bits(&s->gb, buf_ptr+dqt_offs, (buf_end - (buf_ptr+dqt_offs))*8);
  83         s->start_code = DQT;
  84         ff_mjpeg_decode_dqt(s);
  85     }
  86
  87     dht_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "dht is %d and size is %d\n");
  88     av_log(avctx, AV_LOG_DEBUG, "dht offs: 0x%x\n", dht_offs);
  89     if (dht_offs)
  90     {
  91         init_get_bits(&s->gb, buf_ptr+dht_offs, (buf_end - (buf_ptr+dht_offs))*8);
  92         s->start_code = DHT;
  93         ff_mjpeg_decode_dht(s);
  94     }
  95
  96     sof_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
  97     av_log(avctx, AV_LOG_DEBUG, "sof offs: 0x%x\n", sof_offs);
  98     if (sof_offs)
  99     {
 100         init_get_bits(&s->gb, buf_ptr+sof_offs, (buf_end - (buf_ptr+sof_offs))*8);
 101         s->start_code = SOF0;
 102         if (ff_mjpeg_decode_sof(s) < 0)
 103             return -1;
 104     }
 105
 106     sos_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sos is %d and size is %d\n");
 107     av_log(avctx, AV_LOG_DEBUG, "sos offs: 0x%x\n", sos_offs);
 108     sod_offs = read_offs(avctx, &hgb, buf_end - buf_ptr, "sof is %d and size is %d\n");
 109     av_log(avctx, AV_LOG_DEBUG, "sod offs: 0x%x\n", sod_offs);
 110     if (sos_offs)
 111     {
 112 //        init_get_bits(&s->gb, buf+sos_offs, (buf_end - (buf+sos_offs))*8);
 113         init_get_bits(&s->gb, buf_ptr+sos_offs, field_size*8);
 114         s->mjpb_skiptosod = (sod_offs - sos_offs - show_bits(&s->gb, 16));
 115         s->start_code = SOS;
 116         ff_mjpeg_decode_sos(s);
 117     }
 118
 119     if (s->interlaced) {
 120         s->bottom_field ^= 1;
 121         /* if not bottom field, do not output image yet */
 122         if (s->bottom_field != s->interlace_polarity && second_field_offs)
 123         {
 124             buf_ptr = buf + second_field_offs;
 125             second_field_offs = 0;
 126             goto read_header;
 127             }
 128     }
 129
 130     //XXX FIXME factorize, this looks very similar to the EOI code
 131
 132     *picture= s->picture;
 133     *data_size = sizeof(AVFrame);
 134
 135     if(!s->lossless){
 136         picture->quality= FFMAX3(s->qscale[0], s->qscale[1], s->qscale[2]);
 137         picture->qstride= 0;
 138         picture->qscale_table= s->qscale_table;
 139         memset(picture->qscale_table, picture->quality, (s->width+15)/16);
 140         if(avctx->debug & FF_DEBUG_QP)
 141             av_log(avctx, AV_LOG_DEBUG, "QP: %d\n", picture->quality);
 142         picture->quality*= FF_QP2LAMBDA;
 143     }
 144
 145     return buf_ptr - buf;
 146 }
 147
 148 AVCodec mjpegb_decoder = {
 149     "mjpegb",
 150     CODEC_TYPE_VIDEO,
 151     CODEC_ID_MJPEGB,
 152     sizeof(MJpegDecodeContext),
 153     ff_mjpeg_decode_init,
 154     NULL,
 155     ff_mjpeg_decode_end,
 156     mjpegb_decode_frame,
 157     CODEC_CAP_DR1,
 158     NULL,
 159     .long_name = NULL_IF_CONFIG_SMALL("Apple MJPEG-B"),
 160 };